Electric wires used for illumination or decorative string lights must have a certain tensile strength because the wires are provided with decorations. Preferably, they should meet the requirements of U.S. UL 588 for the tensile strength of conducting wires. In general, a conducting wire is composed of a conducting core wire and an insulation cover to wrap the conducting core is wire. A conducting core wire used for string lights may be composed of sixteen conducting monofilaments (bare copper wires) which are stranded together.
In the prior art, the number of the tensile threads are increased to improve the tensile strength of the conducting wire. One way to increase the tensile threads is that the tensile threads and the conducting core wire composed of multiple metal monofilaments are disposed in an insulation cover. Another way is that the tensile threads are directly stranded with the conducting core wire. The way to strand the tensile thread and the conducting core wire is that the tensile thread and the multiple conducting monofilaments of the conducting core wire are stranded together, or the multiple conducting monofilaments are wound on the tensile thread for directly connecting with the conducting wire of a decoration light. A layer or multiple layers of multiple conducting monofilaments are formed on the tensile thread.
However, the conducting wire that the tensile threads and the conducting core wire composed of multiple monofilaments are disposed in an insulation cover has some shortcomings. First, the production efficiency of this conducting wire is less 30% than that of a normal conducting wire. Secondly, during production, the tensile thread may wrap the conducting core wire to bring a non-conducting phenomenon. Thirdly, the multiple tensile threads may scatter and won't be connected with the contact terminals of the lamp socket, without providing the tensile effect. Fourthly, the conducting wire is too hard, which influences the production efficiency of string lights.
The stranding procedure of the tensile thread and the conducting core wire may influence the conductivity of the conducting core wire. In general, the conducting core wire is first stranded and then annealed, such that the diameter of the conducting core wire won't change so as to ensure the resistance of the conducting core wire and the safety of the electric wire. But, the conducting core wire is first annealed and then stranded with the tensile is thread. This cannot ensure the size of the conducting core wire and the demand for the resistance of the conductor. Accordingly, the inventor of the present disclosure has devoted himself based on his many years of practical experiences to solve these problems.